---
res:
  bibo_abstract:
  - "Acquiring, retaining, and retrieving information over a wide range of timescales
    are crucial\r\nfunctions of the brain. The successful processing of memories affects
    many aspects of our\r\nlives and enables us and many other organisms to operate
    in a complex environment and\r\nto interact with it. In this context, the hippocampus
    and functionally connected brain\r\nareas, such as the prefrontal cortex, are
    central and have been subject to intensive research\r\nin the past decades. Storage
    of memories is believed to rely on distributed neural activity\r\nwithin these
    neural circuits. Additionally, neural memory traces of recent experience are\r\nreinstated
    during periods of rest or sleep. These reactivations are thought to play an\r\noutstanding
    role in the consolidation of memories and potentially facilitate the transfer
    of\r\ninformation from the hippocampus to cortical areas for long-term storage
    and integration\r\ninto existing knowledge.\r\nHowever, there is growing evidence
    that memory-related neural representations in the\r\nhippocampus are not as stable
    as initially thought and that they change even in the\r\nabsence of learning.
    It has been suggested that these changes reflect the accumulation of\r\nexperience,
    but the influence of interspersed consolidation periods has not been considered.\r\nPrevious
    studies have analyzed consolidation periods by detecting activity that strongly\r\nresembled
    neural activity during the acquisition of memory. Besides being often limited\r\nto
    only non-rapid eye movement (NREM) sleep, the used approaches were not capable
    of\r\ntracking changes in neural representations over extended temporal periods.
    More fluid\r\nrepresentations do not only challenge our understanding of how information
    is stored, but\r\nthey also affect the transfer of information between brain areas
    during the consolidation\r\nprocess.\r\nFor this thesis, I investigated the evolution
    of memory-related activity during sleep\r\nperiods expected to be involved in
    consolidation in the hippocampus and between the\r\nhippocampus and prefrontal
    cortex. I found that reactivated activity in the hippocampus\r\ngradually transformed
    during prolonged periods of sleep and inactivity. In the beginning,\r\nneural
    activity strongly resembled acquisition activity, whereas, with the progression
    of\r\ntime, it became more similar to the subsequent recall activity. NREM periods
    drove\r\nthis process, while rapid-eye movement (REM) periods showed a resetting
    effect. This\r\nreactivation drift was due to firing rate changes of a subset
    of cells and mirrored the\r\nrepresentational changes from the acquisition to
    the recall. A stable subset of cells\r\nwithstood the drift and maintained their
    activity. Therefore, my results indicate that\r\nmemory-related representations
    undergo spontaneous modifications during consolidation\r\nperiods and that these
    changes are predictive of representational drift.\r\nFurthermore, I found that
    the amount of change in the neural activity during subsequent\r\nsleep periods
    was biased by prior behavioral performance. Observed changes in the\r\nhippocampus
    and the prefrontal cortex were synchronized and increased after poor\r\nperformance,
    highlighting a potential role in the exchange of information. Low-variance\r\nvii\r\nperiods
    with distinct, more stable activity from a subset of cells significantly contributed\r\nto
    the heightened synchrony between both areas. Hence, interleaved phases of more
    stable\r\nneural activity could facilitate the information transfer between brain
    areas.\r\nIn conclusion, my investigations underline the fluidity of memory-related
    representations\r\nand assign a prominent role to sleep reactivation periods in
    their evolution. In addition, I\r\nidentified a potential mechanism of stable
    activity phases that might facilitate the synchronization across hippocampal-prefrontal
    activity despite ongoing changes. Reconciling\r\nand integrating findings from
    both spontaneous and behaviorally-related representational\r\nchanges in functionally
    related brain areas will help to broaden our understanding of how\r\nknowledge
    is stored, maintained, updated, and transferred between brain areas.@eng"
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: Lars
      foaf_name: Bollmann, Lars
      foaf_surname: Bollmann
      foaf_workInfoHomepage: http://www.librecat.org/personId=47AD3038-F248-11E8-B48F-1D18A9856A87
  bibo_doi: 10.15479/at:ista:17346
  dct_date: 2024^xs_gYear
  dct_isPartOf:
  - http://id.crossref.org/issn/2663-337X
  dct_language: eng
  dct_publisher: Institute of Science and Technology Austria@
  dct_subject:
  - Memory
  - Hippocampus
  - Consolidation
  dct_title: Stability and change in the memory system during rest@
...